Spontus

Spontus is a Breton word I learnt recently that means scary or terrible, as in spontus eo an amzer hiziv (the weather is terrible today). It doesn’t sound like it comes from a Welsh or Cornish root, and I wondered where it came from.

According to the Wikeriadurspontus comes from the word spont (to faint/wake with terror) plus the suffix -us. Unfortuantely it doesn’t say where spont comes from. Does any one have any ideas?

Several northern Occitan dialects, Lemosin and Perigordin among them in the northwest, raise all unstressed /a/ vowels to a back mid rounded vowel (not just in word-final position as is otherwise nearly universal in Occitan). I suspect the Breton word might quite likely be an Occitan borrowing, raised-rounded /o/ included, with the adjectival suffix nativised by analogy.

You’re right, the Breton word “spontus” doesn’t look particularly Celtic? But if the word has the same derivation as Christopher’s suggested Occitan espantós, derived from espantar, with the same meaning as well as Catalan espantós (frightening, scary) then “spontus” would have a Romance origin rather than Celtic?
Late Latin *expavento in turn is derived from Classical Latin pavor:
Noun
pavor (genitive pavōris); m. third declension
The act of trembling, quaking, throbbing or panting with fear.
Fear, alarm, terror, fright, panic.
Fear through expectation, dread, thrill, anxiety, trepidation.
Some of the descendants of Latin pavor are:
Catalan: por
French: peur
Friulian: pôre
Italian: paura
Portuguese: pavor
Occitan: paur
Old Provençal: paor
Romanian: pavor
Sardinian: pòre
Spanish: pavor
I don’t know if Breton “spontus” would be related to Welsh poen (pain), poenus (painful), poeni (to pain/worry); or Cornish payn (pain) which is the closest Welsh word I can think of resembling spontus?

Vulgar Latin “expavere” (feel great fear) — from “pavere” (tremble with fear) + the intensive prefix ex- — is the source of the French “épouvanter” (terrify) / “épouvante” (horror). We can also see Italian “paura” (fear) there.

It seems, however, that there was an alternative Vulgar Latin form, “expaentere” — which produced the Portuguese and Spanish “espanto” (fright, horror). I think it’s highly likely that it was from a version of this latter in one of the neighbouring French dialects that Breton got “spont”.

There is an area in Coventry called Spon End. Apparently it used to be full of carpenters yards and the word ‘Spon’ was the name for a wood chipping. I know this probably has nothing to do with your question ;-)